Birzai (Birzai District) - on a white field the arms of
Birzai: on a golden shield a silver banner with a black eagle,
staff of banner red, arms decorated with laurel branches. Flag
proportions 5:7, free edges decorated with golden thread splaying
out diamond-like and framed on both sides with green threads,
fringe is silver, finial is a wooden splay tip with two rings and
golden bands. The arms granted in 1589 symbolize the glory of the
princely Radvila house and of their capital Birzai (more exactly,
Birzai was the capital of Birzai and Dubingiai prinicipality,
ruled by one branch of the Radvila house; another branch ruled
the Nesvizh principality in modern Belarus).Virginijus Misiunas, 31 January 2010